the ipad is still frozen, doesn't respond

Try a "forced restart" using these instructions:

• On an iPad with a Home button: Press and hold the top (power) button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top (power) button. Only when the Apple logo appears, release that button (ignore all other screens that might appear).

Regards

Giulio